Known envelope flaps often have a moisture activated adhesive or a removable barrier over the adhesive (so called peal and stick), or any other included adhesive. Prior to the traditional adhesive strip, flaps were sealed with an external binding connected to both the flap and adjacent side to bind the flap closed. This binding could be melted wax or the like. An affixable seal (e.g. a foil piece with adhesive included on one side), and/or a sticker type item has also been used to seal (or double seal in conjunction with included flap adhesive) envelope flaps. U.S. Pat. No. 2,367,440 describes a self-sealing paper envelope. Also, U.S. Pat. No. 5,429,576 describes a reusable adhesive envelope having a pressure sensitive adhesive, which is initially covered by a release liner. Upon removing the release liner the adhesive on the flap may be secured to the protective strip to close the flap, which may be opened and closed numerous times.
Users of envelopes will sometimes double seal an envelope to ensure it does not open during transit, or otherwise increase the effectiveness of the closure seal. A deficiency of the most common included adhesive, i.e., moisture activated adhesives, is that a heavy humidity, heat, or other environmental condition can weaken or even release the closure seal, thereby opening the envelope during transit. To strengthen the seal, a user may apply some tape or a sticker across the flap and adjacent side in order to deter this deficiency of just the flap adhesive alone. U.S. Pat. No. 913,987 describes an envelope where projecting tongues are adapted to fold over the sealing flap after the latter is folded and sealed, and thus firmly secure the sealing flap and prevents it from being opened. U.S. Pat. No. 3,702,171 describes an envelope with superimposed strips aligned to be partially lifted and placed back down on the flap to seal the envelope. A problem with these known envelopes is that they can add complexity to the manufacturing process. Additionally, as the releasable adhesive layer is placed on a wall of the envelope after the envelope has been manufactured, the releasable adhesive can add a non-uniform thickness to the envelope, making it difficult to store multiple envelopes on top of each other.
Thus, is may be desirable to provide an envelope having a removable adhesive strip for additional sealing of the envelope that can be integrated into one of the walls of the envelope. It is further desirable to provide an envelope that can be easy to manufacture, and that can be made from a continuous sheet of material.